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ISS NASA Space Technology

Smooth, 6.5 Hour Spacewalk To Fix ISS Ammonia Pump 90

Posted by timothy
from the easy-peasy-space-is-breezy dept.
The ISS crew can breathe a little easier now; the NY Times reports that the ammonia pump repair that the station has needed has now been partly completed, and in less time than expected. More work is scheduled, but, says The Times: "The astronauts, Col. Michael S. Hopkins of the Air Force and Richard A. Mastracchio, were far ahead of schedule throughout the spacewalk as they detached tubing and electrical connectors from the pump. They were able to remove the 780-pound module and move it to a temporary storage location, a task that had been scheduled for a second spacewalk on Monday. ... Colonel Hopkins and Mr. Mastracchio stepped out of an airlock at 7:01 a.m. Eastern time, and even though they accomplished more than they had set out to do, they were able to return at 12:29 p.m., an hour earlier than had been scheduled. The two encountered few complications." Ars Technica has video, too.
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Smooth, 6.5 Hour Spacewalk To Fix ISS Ammonia Pump

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  • by Deadstick (535032) on Saturday December 21, 2013 @05:26PM (#45756141)

    This is low earth orbit, not the moon.

  • Re:I'm curious... (Score:5, Informative)

    by cbhacking (979169) <been_out_cruisin ... y a h o o . c om> on Saturday December 21, 2013 @07:49PM (#45756893) Homepage Journal

    The heat sink in your computer would be pretty miserable at dumping waste heat into space. Terrestrial heat sinks typically heat into a fluid, such as the air that your computer's fans blow across the heat sink.

    Problem: there is no air (or anything else into which heat may be transferred) in space. Radiative cooling - that is to say, releasing infrared radiation - does occur, but it is *far* slower that conductive cooling. To do that effectively, though, you want a big, hot surface area that is shadowed from all other heat sources in the region (that big fusion reactor the Earth orbits counts as "in the region" here).

    To cool an artificial satellite effectively, especially a big one like ISS, you use a heat transfer system (in this case, they apparently use ammonia) to concentrate the heat into radiative cooling surfaces on the shadowed side of the station. This system definitely adds complexity, not to mention generating a bit of heat itself(entropy always increases), but without it, the side of the station facing the sun would cook, and the shadowed side wouldn't get hot enough for effective radiative cooling.

  • by ClickOnThis (137803) on Saturday December 21, 2013 @10:55PM (#45757661) Journal

    ....while in orbit, where they don't feel the effects of gravity?

    They don't feel the effects of gravity, but they very much feel the effects of inertia.

    In this context (i.e., earth orbit) the 780 lbs of the module refers to mass rather than weight. If the module were drifting and they had to stop it by grabbing it while they were connected to the ISS, you can bet they'd feel the effects of inertia. For the two-dimensional analogy, imagine a refrigerator, sliding on a perfectly slippery ice rink.

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